Dramatic advances in the survival rates of extremely immature infants over the past five years have resulted in an increase in the number of cases of retinopath of prematurity that are being seen. The apparent inevitability of this retinopathy in the smallest infants is frustrating, but should be amenable to study and possibly prevent or improved treatment. It is our hypothesis that the current management of premature infants, which utilizes the lowest possible arterial oxygenation, will aggravate this retinopathy once it has begun, possibly converting mild disease to severe disease. We propose to test this hypothesis in the kitten model of oxygen induced retinopathy by studying the retinopathy that occurs after a hyperoxic insult, comparing various recovery period treatments, (hypoxia, tapering hyperoxia and variable oxygenation). Should this hypothesis prove true, the clinical management of human premature infants will have to be reexamined, and it is possible that the visual outcome in these infants may be improved.